Nuclear Magnetic Resonance: An Introduction

Nuclear magnetic resonance or NMR is one of the most widely used discoveries of Modern Physics. NMR is based on the bulk magnetic properties of materials made up of certain isotopes, most notably, protons (1H), but encompassing a wide variety of species including C, F, and Si. NMR is used to measure magnetic fields with exquisite precision. NMR is used in chemical analysis, oil exploration, and, of course, is the basis of MRI — magnetic resonance imaging. Nuclear magnetic resonance is not just a bulk effect. The dynamics of a nuclear spin subjected to static and time dependent magnetic fields are described by quantum mechanics, and for the case of a spin 1/2 nucleus such as 1H, can be described by classical electrodynamics. Both of these descriptions are useful and important for a full understanding of NMR. Bulk NMR effects are most apparent in the classical context of magnetic materials. There are currently two NMR experiments available in this lab. Pulsed NMR, demonstrates the dynamics of nuclear spins and is the basis of many modern NMR based instruments. Continuous wave (CW) NMR is based on the bulk features of a sample of nuclear spins. An NMR imaging experiment is currently under development. This chapter serves as the introduction to all of these experiments.